JP2008052947A - Charged particle beam device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shoot a charged particle beam to a predetermined position. <P>SOLUTION: An electron optics lens barrel 1 having an electron optics system such as an electron gun, a focusing lens and a deflector is mounted on a plotting chamber 2, and an electron beam from the electron gun is shot to the predetermined position on a plotting object material 3 set on a stage 7. The stage 7 can be moved by operation of a driving motor 8. A case 4A of an ion pump 4 having the case 4A storing a cathode and an anode and a yoke 4C fixed with a magnet 4B, is installed in the lens barrel 1 via an exhaust pipe 5. One end of a support member 6 is installed in the yoke 4C, and the other end of the support member 6 is installed on an upper wall of the plotting chamber 2. A space is arranged between the case 4A and the magnet 4B and between the case 4A and the yoke 4C, and dampers 14A, 14B and 14C are interposed in the respective spaces. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charged particle beam apparatus provided with an ion pump.

  There is a charged particle beam apparatus that uses a charged particle beam such as an electron beam or an ion beam to observe a sample or draw a pattern on a material.

  For example, the electron beam drawing apparatus is one of charged particle beam apparatuses, and the electron beam drawing apparatus will be briefly described below.

FIG. 1 shows an outline of an electron beam drawing apparatus. Reference numeral 1 denotes an electron optical column mounted on a drawing chamber 2. In the electron optical column 1, an electron gun (not shown), a focusing lens (not shown) for focusing an electron beam from the electron gun on a sample, and the focused electron beam A deflector (not shown) for scanning a predetermined area on the drawing material 3 disposed in the drawing chamber 2 is provided. Further, an ion pump 4 (for example, a sputter ion pump) for making the inside of the lens barrel 1 and the drawing chamber 2 high vacuum is attached to the side wall of the electron optical lens tube 1 through an exhaust pipe 5. . The ion pump includes a case 4A containing a cathode and an anode, a magnet 4B, and a yoke 4C. The magnet 4B is attached to the yoke 4C, and the yoke 4C is fixed to the case 4A.
In the figure, reference numeral 6 denotes a support member that supports the ion pump 4 in order to prevent the load of the ion pump 4 from being applied to the lens barrel 1 and has a trust structure, and supports the yoke 4C at one end thereof. The other end is fixed to the upper wall of the drawing chamber 2.

In the drawing chamber 2, a stage 7 for placing the drawing material sample 3 is provided. A driving motor 8 for moving the stage 7 is attached to the outer wall of the drawing chamber 2, and a moving body 10 made of a female screw is connected to the stage 7 via a connecting body 9. The stage 7 is linearly moved by screwing a body into a ball screw 11 connected to the shaft of the drive motor 8 and rotating the ball screw 11 by the operation of the drive motor 8. Reference numerals 12 and 13 denote bearings, and the drive motor 8, the coupling body 9, the moving body 10, and the ball screw 11 constitute a stage drive mechanism.
The deflector includes an X-direction scanning device and a Y-direction scanning device, and the stage and the stage driving mechanism have been described only in one direction. Are both made for movement in the X direction and for movement in the Y direction.

  In such an electron beam drawing apparatus, the inside of the electron optical column 1 and the drawing chamber 2 are brought into a predetermined high vacuum state by the ion pump 4. In this state, an electron beam from an electron gun (not shown) is focused on the drawing material 3 by a focusing lens (not shown), and a deflector (to which a position signal generated based on pattern data is supplied). A predetermined pattern is drawn at a predetermined position on the material 3 to be drawn by causing the electron beam to be shot at a predetermined position on the material 3 to be drawn.

When such pattern drawing is performed in an area of a predetermined size, that is, an area where deflection distortion is allowed and pattern drawing is performed in the next area, an electron gun (not shown) is temporarily used. The electron beam from is blanked on (blanking is applied), and during the blanking on period, the stage drive mechanism is operated to move the stage 7, and the central axis of the electron beam is to be drawn next. To come to the center of Then, with the stage stopped, the electron beam blanking is turned off (blanking is removed), and a pattern is drawn in that region.
Such a drawing method is a well-known step-and-repeat drawing method, but there is also a continuous running drawing method in which a pattern is drawn while the stage 7 is continuously moved at a constant speed. Also in this case, the stage 7 is moved by the stage driving mechanism.
In any drawing method, the stage 7 can be moved. When the stage 7 is moved, the natural vibration of the ion pump 4 is caused by the inertial reaction force of the stage 7 and the vibration of the drive motor 8. Is excited, a force is applied to the lens barrel 1 through the exhaust pipe 5 due to the vibration of the ion pump, and the lens barrel 1 may be bent.
When the lens barrel 1 is bent in this manner, the trajectory of the electron beam from the electron gun (not shown) is changed, and the shot position of the electron beam on the drawing material 3 is deviated from the predetermined position. Accuracy will be reduced.
In order to obtain high drawing accuracy without causing such a reduction in drawing accuracy, it is necessary to wait for the natural vibration of the ion pump 4 to attenuate and become small. However, the magnet 4B and the yoke 4C constituting the ion pump 4 are quite heavy from several kg to several tens kg, and a plurality of natural frequencies of the portion including the exhaust pipe 5 are generated between 30 Hz and 100 Hz, and once vibrate. As a result, the throughput for pattern fabrication decreases.
There is a method of increasing the natural frequency as a method of speeding up damping of vibration. The truss structure support member 6 is intended to increase the natural frequency of the ion pump 4 by increasing the rigidity of the support structure of the ion pump 4 so as to accelerate the attenuation of the natural vibration of the ion pump.

JP-A-9-197091

However, since such a support member 6 is connected to the lens barrel 1 via the ion pump 4, when the support member 6 receives external vibration and vibrates, the vibration is transmitted to the lens barrel via the ion pump 4. 1, leading to a reduction in drawing accuracy.
Further, the lens barrel 1 itself has a natural frequency of about 60 Hz to 200 Hz, and the movement of the stage 7 excites such a natural vibration, leading to a reduction in drawing accuracy.
It is an object of the present invention to provide a novel charged particle beam apparatus that solves such problems.

  The charged particle beam apparatus according to the present invention includes an electron optical column having an electron optical system such as a charged particle beam generating unit, an electron lens, and a deflector on a column mounting base, and from the charged particle beam generating unit. The charged particle beam is irradiated onto a beam irradiation object set on a stage moved by a movement drive mechanism, and includes a case containing a cathode and an anode, and a yoke to which a magnet is fixed. In the charged particle beam apparatus in which the case of the pump is attached to the lens barrel via an exhaust pipe, and the yoke is attached to a support member provided separately from the lens barrel, between the case and the magnet, and the case And a yoke, and a damper is interposed in at least one of the spaces.

  According to the charged particle beam apparatus of the present invention, even if the natural vibrations of the exhaust pipe connected to the lens barrel and the case of the ion pump are excited by the movement of the stage, the mass of these parts is the whole of the exhaust pipe and the ion pump. Therefore, the excited natural frequency becomes high and attenuates in a short time. As a result, highly accurate drawing is possible.

  Further, even if the natural vibration of the lens barrel is excited by the movement of the stage, thereby causing the exhaust pipe and the case to vibrate, and the relative vibration is generated between the case and the magnet and the case and the yoke, the case, the magnet and the case The natural vibration of the barrel is suppressed by the damping capacity of the damper interposed between the yoke and the yoke. As a result, highly accurate drawing is possible. Further, the natural vibration of the exhaust pipe and the case is also quickly damped by this damper, and as a result, highly accurate drawing is possible.

  Furthermore, even if the support member receives external vibrations and vibrates, the damper suppresses vibration transmission to the case and blocks vibration transmission to the lens barrel. As a result, highly accurate drawing is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 shows a schematic example of an electron beam drawing apparatus as an example of the charged particle beam apparatus of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components.

  The apparatus shown in FIG. 2 is different from the apparatus shown in FIG. 1 in the following configuration.

In the apparatus shown in FIG. 1, the yoke 4C is fixed to the case 4A, and the support member 6 is connected to the lens barrel 1 through the ion pump 4 and the ion pump 4 by supporting the yoke with the support member 6. On the other hand, in the apparatus of FIG. 2, the yoke 4C to which the magnet 4B is attached is separated from the case 4A, a space is provided between the yoke and the case, and the exhaust pipe 5 is substantially connected to the lens barrel 1. Only case 4A via
The space between the yoke 4C and the case 4A and the space between the case 4A and the magnet 4B are each made of, for example, a viscoelastic material (polymer material or rubber-based material as a main raw material). Dampers 14A, 14B, and 14C are interposed.
The support member 6, the magnet 4 </ b> B, and the yoke 4 </ b> C that are directly connected to each other are designed so that their natural frequencies are higher than the bending frequency of the lens barrel 1.
In such an apparatus, when the stage 7 moves, the natural vibration of the exhaust pipe 5 connected to the lens barrel 1 and the case 4A portion of the ion pump 4 is excited by the inertial reaction force of the stage and the vibration of the drive motor 8. Is done. However, since the mass of these parts is a fraction of the mass of the exhaust pipe 5 and the ion pump 4 as a whole, the excited natural frequency is several times higher and attenuates in a short time of a fraction.

  When the natural vibration of the lens barrel 1 is excited by such a stage movement, the exhaust pipe 5 and the case 4A vibrate due to this vibration, and the case, the magnet 4B, the case, and the yoke 4C Relative vibration occurs during However, the natural vibration of the lens barrel 1 is suppressed by the damping ability of the interposed dampers 14A, 14B, and 14C. The natural vibration of the exhaust pipe 5 and the case 4A is also quickly damped by the damper.

  Even if the support member 6 is vibrated by external vibrations, vibration transmission to the case 4A is suppressed by the interposed dampers 14A, 14B, and 14C, and vibration transmission to the mirror body 1 is blocked. Is done.

  In the above example, the electron beam drawing apparatus has been described as an example. However, other charged particle beam apparatuses such as a scanning electron microscope and a focused ion beam are used to observe or process a sample image. The present invention is also effective for an apparatus that performs the above-described process.

1 shows an outline of an electron beam drawing apparatus. 1 shows an example of a charged particle beam apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electro-optical column 2 ... Drawing chamber 3 ... Drawing material 4 ... Ion pump 4A ... Case 4B ... Magnet 4C ... Yoke 5 ... Exhaust pipe 6 ... Support member 7 ... Stage 8 ... Drive motor 9 ... Connection body 10 ... Movement Body 11 ... Ball screw 12 ... Bearing 13 ... Bearing 14A, 14B, 14C ... Damper

Claims (4)

  An electron optical column equipped with an electron optical system such as a charged particle beam generating means, an electron lens and a deflector is mounted on the lens barrel mounting base, and the charged particle beam from the charged particle beam generating means is moved by a moving drive mechanism. The irradiation object to be irradiated set on the stage to be moved is irradiated, and the case of the ion pump having a case containing the cathode and the anode and a yoke to which the magnet is fixed is passed through the exhaust pipe. In the charged particle beam apparatus in which the yoke is attached to a support member provided separately from the lens barrel, a space is provided between the case and the magnet, and between the case and the yoke. A charged particle beam device in which a damper is interposed in at least one of the spaces. The charged particle beam apparatus according to claim 1, wherein the damper is made of a viscoelastic body. The charged particle beam apparatus according to claim 1, wherein the support member has a truss structure. The charged particle beam apparatus according to claim 1, wherein one end portion of the support member is attached to the yoke, and the other end portion is attached to the lens barrel mounting table.

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